What is a gun magazine catch?

A gun magazine catch, also known as a mag catch or magazine release, is a mechanical device used to hold a detachable magazine in place in a firearm. When a magazine is inserted into the firearm, the magazine catch engages with a corresponding notch or slot in the magazine, preventing it from falling out. When the magazine release button or lever is pressed, the magazine catch is disengaged, allowing the magazine to be removed. Magazine catches are typically located at the bottom or side of the firearm's grip or receiver. The design and location of magazine catches can vary depending on the make and model of the firearm.